Fluidic or/nor gate



C Umted States Patent [1113,543,780

[72] Inventor Charles J. Ahern [56] References Cited Sidney, New YorkUNITED STATES PATENTS [2 1 pp 731707 3,107,850 [0/1963 Warren et al.l37/8l.5X 1 PM 3,240.219 3/1966 Dexter et al. 137/315 {45] Patented Dec.1, 1970 I I [73] Assignee The Bendix Corporation PrunaryExammer--W1ll1am R. Clme a corporation f Delaware Att0rne vsWilliam S.Thompson and Flame, Arens, Hartz and OBrien ABSTRACT: A multiple-inputmonostable fluidic OR gate which uses segregated inputs to avoid thegeneration of spurious signals being transmitted to other stages of thecircuit and which employs a cusp on the wall opposing the inputs toFLUIPIC oR/NQR prevent overdriving of the OR output. To provide OR/NOR 51 Draw operation, an attachment wall is provided on one side of the [52]US. CL... 137/815 fluid reaction area and a vent is provided on theother side so 5 1m, (3] FlSc 1/10 that uncontrolled fluid flow shows apreference for the output [50] Field of Search 137/315 passagedownstream of the attachment wall.

NOR 0 Patented Dec. 1,1970 U f 3,543,780

CHARLES s. AHERN INVENTOR.

FLUIDIC OR/NOR GATE BRIEF SUMMARY OF INVENTION The presentstate-of-the-art multiple input OR gates exhibit one or the other oftwofaults which seriously limit their applications. One of these faults isthe relative impositiveness in switching exhibited by devices whichstructurally resemble proportional amplifiers. The other of these faultsis the loss of control fluid and signal experienced by monostable gateshaving vented reaction chambers and overly powerful control pulses. Itis, therefore, an object of this invention to provide a fluidic OR/NORgate having neither of the above-mentioned faults. Since OR/NOR gatesare known in which the multiple control passages are joined to form asingle control port and these gates have the additional fault ofgenerating spurious signals in the balance of the system in which theyare used, it is a further object of this invention to provide a fluidicOR/NOR gate which does not generate spurious signals in otherportions ofthe circuit in which it is used, and which has a sharp switchingcharacteristic and does not suffer from fluid or signal loss in theevent of overdrive by the controls It is an ob ject of this invention toprovide a fluidic monostable OR/NOR gate having multiple inputs which isnot subject to the generation of spurious signals and which does notsuffer from pressure source fluid loss in the event more than onecontrol signal is present.

It is a further object of the present invention to provide an OR gatewhich is insensitive to pressure changes in controlfluid pressure over awide range of pressures. It is a still further object ofthe presentinvention to provide a multiple input OR gate in which control signalsin one of the control passages will not generate spurious signals in anyof the other control passages.

BRIEF DESCRIPTION OF THE DRAWING The FIG. shows a multiple-input OR/NORgate, in stylized representation, made according to the teachings of thepresent The drawing shows a fluidic OR/NOR gate made according to thepresent invention and having an inlet port for supplying a source ofpressurized fluid, P The port 10 communicates with nozzle 12, throughpassage 14, for issuing a power-fluid stream into the fluid reactionarea, designated generally as 16. The reaction area 16 includes meansestablishing an output passage preference in the form of vent l8 andattachment wall to encourage a power-fluid stream issuing from nozzle 12to flow through the reaction area 16 and out via output passage-22,labeled the NOR passage.

As is well known, the Coanda effect causes fluid flowing past a wall tobecome attached to the wall by aspirating the region between the flowand the wall, thus creating a low pressure region. Attachment wall 20 isprovided for that purpose and vent 18 is provided to eliminate thepossibility of wall attachment occurring on side wall 32 of the reactionarea 16. The power-fluid stream, thus, shows a preference for the outputpassage 22.

Communicating with the reaction area in the vicinity of the attachmentwall 20 are a multiplicity of control passages, here shown as twopassages, 24 and 26. While only two are shown, it should be apparentthat it would be possible to employ other than that number of controlpassages. A second output passage 28 is also shown in communication withthe reaction area and is labeled the OR passage.

In the reaction area 16, downstream of the vent l8 and upstream of theoutput passage 28, is located an overdrive control shown as cusp 30. Thecusp 30 is arranged in an intercept ing location with respect to thecontrol passages 24 and 26 to intercept fluid flowing from the controlpassages and to redirect it back into the reaction area 16, in the eventthat more than one control passage has a control fluid flow or a singlepassage has an overly strong signal present in it.

OPERATION In operation, the gate functions thusly. A source of pres Isurized fluid, P,, causes a power stream of fluid to issue from thejet12 into the reaction area 16. In the absence ofa control signal fromeither of the control passages, the power stream will have an affinityfor the NOR output passage 22 and will wall 32 cooperate to produce asharp switching characteristic,"

whether the switching is to take place from NORtoOR or from OR to NOR.However, the attachment wall 20 isimpor tant by itself to give the gatea monostable operating characteristic. Thevent 18, by itself, isnecessary to prevent an overly long control signal or immediatelyconsecutive control signals from holding the fluid stream in thenonpreferred position for a sufficiently long period of time to allowthe power fluid stream to aspirate the region between the fluid streamand side wall 32. Without the vent, the Coanda effect would causefluidstream attachment to wall 32.

When a control pulse appears in either of the passages 24 or 26, thepressure in the aspirated region is rapidly elevated to break the wallattachment and then to physically shift the power fluid by momentumtransfer, from the NOR output channel 22 to the OR output channel 28. Ifan additional control pulse should now appear, or if two should appeartogether in the control passages 24 and 26, the resultant controlpressure on the power fluid stream issuing from nozzle 12 would tend tooverdrive it. That is, instead of merely shifting the flow from channel22 to channel 28, the control pulse would tend to force the powerfluidstreamer beyond channel 28 until a portion of the power-fluid streamentered the vent 18. The cusp 30 is operative to prevent this byproviding passive overdrive control.

As the power fluid stream begins to switch from channel 22 to channel28, the presence of additional control pulses in passages 24 and 26would have noticeable effect. However, additional control pulses causethe power-fluid stream to attempt to move further to the right (withrespect to the FIG. in the drawing) than is ordinarily the case. As thepower-fluid steam attempts to move further to the right, a portion ofthe power-fluid stream which now includes control fluid, is diverted bythe cusp 30 and redirected against the main fluid stream in a generallyopposing manner to the control pulses. The stronger these control pulsesare and the further to the right the fluid stream is urged, the greateris the effect of the cusp 30 in diverting and redirecting greateramounts of fluid from the main fluid stream.

In the event that only a single control signal appears. the power-fluidstream would flow out of control 28 without any involvement of theoverdrive control cusp 30. This means that signal is undiminished bydiversion of fluid by the cusp 30 until more than one control signal isreceived by the control passages 24 and 26 and the fluid diverted by thecusp diminishes the power-fluid stream to an extent only approximatingthe momentum added by the additional control signal. Therefore, even inan overdriven condition, the strength of the power-fluid stream remainsvirtually undiminished.

Thus, the invention accomplishes its stated objectives. The devicemaintains its monostability of operation under all operating modes andis not subject to fluid or signal loss in the event of coincidence ofcontrol pulses.

Iclaim:

l. A fluidic OR/NOR gate comprising:

a source of pressurized fluid in communication. through a fluid jetpassage, with a fluid reaction area;

a vent means arranged in the fluid reaction area. to one side of, anddown stream from said fluid jet passage;

control passage means arranged in the fluid reaction area downstreamfrom said fluid jet passage and to a side thereof opposed to said vent;

two output passage means downstream from said vent and said controlpassage means; and passive fluid overdrive control means positioned tosaid one side downstream from said vent and upstream from said outputpassage means operative to provide a countercontrol fluid pressure inthe'event overdrive of said source occurs. 1 2. The gate, as claimed inclaim 1, wherein said passive fluid overdrive control means comprises acusp located in proximity to the downstream juncture of said vent andsaid fluid reaction area and downstream from said vent. J

3. The gate, as claimed in claim 1, including further an attachment walldownstream of said passage means control.

4. A fluidic gate comprising: a fluid reaction area; 7 a source ofpressurized fluid fluid through a nozzle into said fluid reaction area;

for ejecting a first: stream of p output passages connected to saidfluid reaction area and adapted to exhaust said first stream from saidfluid reaction chamber; v

control passage means connected to said fluid reaction area and arrangedgenerally transverse to and on one side of said first stream;

a vent passage connected to said fluid reaction area and arrangedgenerally transverse to said first stream and in opposition to saidcontrol passages; and

an overdrive control cusp located in said fluid reaction area inproximity to said vent downstream from said -vent passage and upstreamfrom said output passages. v

5. The a gate, as claimed in claim 4, wherein said fluid reaction areaalso includes output passage preference means in cooperative associationwith said control passages.

